The present invention relates to an apparatus for heating water for producing a hot water and steam mixture and a cleaner utilizing the mixture. The apparatus further recovers dirty water from the article being cleaned and recovers heat from the dirty water to preheat incoming fresh water.
Steam cleaning devices are becoming very popular for use in cleaning a wide variety of items, especially rugs, but also including upholstery, fabric covered furniture and the like. Because many of the items to be cleaned are permanently installed or difficult to move, the steam cleaning apparatus must usually go to the site where cleaning is to occur. Consequently, the apparatus for many modern cleaners of this type is truck mounted.
Throughout the day a truck mounted cleaning unit will be required to produce a substantial amount of high pressure hot or even super heated water and/or steam. Normally, this water is originally supplied to the truck at the site of the cleaning through a hose, but may be carried to the site, if water is not available. As this water is usually at an ambient temperature or cooler, the water must be heated substantially by the apparatus in order for it to be usable.
One of the most common ways of heating water for this purpose is by means of a hydrocarbon fueled internal combustion engine. In particular, heat produced by the engine, especially the exhaust is transferred to the water. However, a substantial amount of the heat generated by the engine is wasted making it difficult for even a large engine to produce enough heated water to keep up with a heavy demand which in turn slows work or requires replacement of the engine with a larger engine having a greater purchase cost and a greater operating cost.
Consequently, it is desirable to make highly efficient usage of a smaller engine with a relatively low operating cost.
One of the inefficient features of the prior art devices used for this purpose has been that, while exhaust has been used to heat the water, the heat exchanger for heating the water with the exhaust is normally substantially removed from the engine exhaust parts. This is done to allow the exhaust gas to cool in the exhaust manifold before entering the heat exchanger, as the gas directly exhausting the manifold are hot enough to melt or deform conventionally used heat exchangers.
Secondly, once the exhaust gas leaves the primary heat exchanger it is normally simply wasted.
Thirdly, waste water and steam that are recovered by vacuum after cleaning are not used further and the residual heat therein is wasted.
Fourthly, the waste water returning from the cleaning process with dirt and the like is drawn by a vacuum compressor. When operating under a load, especially heavy loads, the vacuum compressor further heats the air, water and steam being drawn through the compressor. In conventional systems this heated air and water is wasted.